Chair with automatically shiftable seat and adjustable back



ep 5 R. A. CRAMER 2,609,032

CHAIR WITH AUTOMATICALLY SHIFTABLE SEAT AND ADJUSTABLE BACK Filed Dec. 1, 1950 5 Sheets-Sheet 1 .fil'f. 1

IN VEN TOR.

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A TTOF/I/[YS P 1952 R. A. cRAMER 2,609,032

CHAIR WITH AUTOMATICALLY'SHIFTABLE SEAT AND ADJUSTABLE BACK Filed Dec. 1, 1950 3 Sheets-Sheet 2 Q K r I *2 IN V EN TOR.

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p 2, 1952 R. A. CRAMER 2,609,032 f CHAIR WITH AUTOMATICALLY SHIFTABLE SEAT'AND' ADJUSTABLE BACK Filed Dec. 1. 1950 a Sheeis-Sheet .5

iilllllli IN VENTOR.

Patented Sept. 2, 1952 UNITED STATES PATENT OFFICE onen WITH AUTOMATICALLY SHI'FTABLE lioy Qramer, Kansas City, Mo. Application December 1, 1959, Serial No. 198,654;

wa'rd-ly'and the forward portion upwardly and the back portion tilts backwardly conforming to the back of the user at the extreme back tilting movement; to provide a mounting for the seat wherein the weight of the user will cause a substantially balanced action of the seat on the mounting mechanism wherein slight pressure backward on back of the chair will cause the seat tomove forwardly and the front portionupwa-rdly thus securing a natural pivotal action of the upper and lower portions of the users body; to provide means mounted on the tilting mechae nism frame for adjustabl-y and tiltably mounting the back of the chair thereto; to provide a frame for the seat of the chair; to provide means for slidably mounting the seat frame on the tilt ing mechanism frame for moving the seat portion forwardly or backwardly relative to the back of the chair; to provide means for resiliently mounting the back of the chair with respect to the tilting mechanism; to provide spring tension means for varyi-ngshiftability of the chair seat; and to provide for mechanical adjustment of the tilting back mechanism.

Further objects of thepresent invention are to provide means for providing the correct balance of the chair and its occupant with respect to the chair base at various angles of tilt of the chair back; to provide means for mounting the tilting mechanism ro'tata-bly on the standard and base of the chair; to provide a cam roller mounting means for the seat operable in traclrways so that when the user shifts his Weight rearwardly the seat and back will tilt backwardly and shift forwardly to substantially the users center of grave ity to the vertical center of the swivel member support to produce a comfortable shifting movement and reduce thehazard of tipping the chair over backwards; to provide adjustable spring tension means for shifting movement of the tr-ackw-ays in the seat tilting mechanism with re spect totheicam rollers; to provide shock absorbers' atthel-imitsof the cam track movements; l m m a bumper onthe lower edge of t e eat o revent m r es o a icle g ne al y can sted by sur oundin obje t a d to p id a ha r of is character s mp e. con ica 1 9.

facture nd ef c ent i perat on- In accomplishing these and other objects of e sent n n i n I h ov ded more d details of structure, the preferred forms ofwh r us at i the accom a g drawin s is r:

'Fi i a tion."

side elevational view of my invent:

Fis- 2 is an enlar d s e eva o asset and back portion with parts broken away to better illustrate the invention. Fig. 3 is a bottom plan view of the seat. Fig. 4 is a sectional View or; the line 4:4, Fig.

Fig. 5 is a perspective viewof the spiderfor supporting the seat, Showing the tension springs,

ne s ri g ghpwn n s ce ela ionthereto.

Fig. 6 is a transverse se tional view through the forward portion of the housing containing the tilting mechanism. Fig. 7 is a sectional view taken on the line Ir-'1 Fig. 3 showing the position of the cam tracks rel.- ative to the roller wheels when the chair is in normal position.

Fig. 8 is a sectional view similar to Fig. 7 she-wi e posit on o seat is tilted;

Referring more in detail to the drawings:

l d si a ch m d n e ea ures-- of my invention comprising a base 2, a pedestal or standard 3 suitably mounted in the base for sup ortin a tiltin m cha ism 4 or u rtin a seat 5 on which are mounted arms Band 1 and a n a a k 8' The base 2 consists of a plurality of radiating arms :9 the outer ends being curved downwardlyand mounted therein are casters iii. The base is cast in one piece and includes a depending housing I I and an upstanding boss i2 at the top of the base, the housing being hollow and ac--:

mmod t the an d 3 u ed he e n-1 A ide i s r d fo m u in 9f the l in mechani m an so r or in o he seat 5 as will later be described. The spider [3,

m r se a body rt o a in n i ce a d has depending sides I4 and I5 fiared outwardly forming a forward portion 16 and having a, pair of arms I! and I8 extending outwardly with the rear thereof terminating in a cross member '13. Formed approximately at the juncture of the;

ms 1 an t a d h d nse-din si es i sol '5 o he bodo the s d is a de nd ng 1 914 1 the cam tracks when the 3.. ing 20 providing a socket 2| for receiving the upper end 22 of the standard 3 to rotatably mount the tilting mechanism on the standard. Located near the upper end of the standard 3 is an annular groove 23. The rear of the housing 2| is provided with a transverse threaded opening 24 adapted to receive a set screw 25 having its inner end engaging in the annular groove 23 for retaining the spider on the standard.

The forward portion I6 of the spider has a downwardly extending flange 26 the ends of which are connected with outwardly flared sides I4 and I of the spider by blocks which form supports 21 and 28 for a shaft 29. The shaft 29 extends through the supports transversely of the spider and mounted on the ends of the shaft 29 are ball bearing cam rollers 30 and 3|. The rear portion I9 of the spider is similarly provided with supports 32 and 33 for a shaft 34 which extends outwardly from the supports and mounted on the ends of shaft 34 are ball bearing cam rollers 35 and 36. The rear portion I9 of the spider is provided with upstanding flange portions 31 and 30 which are provided with cylindrical recesses '39. The recesses are provided with radial slots 40, as best. illustrated in Fig. 5, for a purpose later described.

A housing 4| is provided for the tilting mechanism which is substantially rectangular in shape and has depending sides 42 and a forward end 43. The rear portions of the side are tapered as indicated at 44 (Fig. 8) and the extreme rear end is flanged downwardly at an angle, as indicated at 45. The housing is provided with a substantially flat top 46 having an embossed portion forming a raised plate member 4'! (see Figure 4) for a purpose later described.

Secured to the inner portions of the respective sides 42 of the housing by welding or other suitable means are cam track plates 48 and 49 having inwardly turned upper and lower flanges 50 and 5| forming trackways 52 for the cam rollers 30 and 3| at the forward portion of the housing for the tilting mechanism. The cam plates are provided with enlarged portions 53 at their rear ends and the lower edges thereof are arcuately tapered as indicated at 54 (Figs. 7 and 8) which are also flanged as indicated at 55 and form bearing surfaces 56 for the cam rollers 35 and 36. The enlarged ends 53. of the cam tracks are provided with reenforcement plates 51 and are secured to the cam plates by welding or the like. The plates have a flange conforming to the flange in the enlarged portion of the cam plates to provide further reenforcement thereof. A retainer plate 59 is provided for the rollers 35 and 36 for forming a trackway 60 for the rollers 35 and 36. The plate has its ends turned upwardly forming flanges 6| for securing the plate to the housing by set screws or the like, as indicated at 62 (Fig. 2). The plate 59 is provided with a reenforcing rib 63 to lend rigidity to the structure and retain the rollers in the trackway 60.

The supports 21 and 28 on the forward portion I6 of the spider are provided on the underneath side adjacent of the cam rollers with threaded sockets adapted to receive the shanks of the trunnions 64 for mounting of ball bearing rollers 65 and 66 which engage against the edges 61 and 68, respectively, of the inturned flanges 5| on the track plates, as best illustrated in Fig. 6, to pre vent lateral movement of the spider in the housing 4|.

The supports 32 and 33 of the rear portion I9 of the spider are also provided with threaded 4 bores adapted to receive the threaded shanks of trunnions 69 for mounting ball bearing rollers II and 12, also for prevention of lateral movement of the rear portion of the spider in the housing.

A bumper I3 is secured to the down turned flange 45 of the rear end of the housing by brackets I4 secured to the flange by screws 15. The bumper is hollow and the brackets extend into the ends thereof to retain the bumper on the flange so that the rear portion I9 of the spider will engage thereagainst to provide a cushion therefor. A bumper I6 is also provided at the forward end of the spider and is secured to the end 43 of the housing in a similar manner to the rear bumper as just above described, the forward bumper being in substantial alignment with the forward ends of the track-ways in the cam plates.

The end 43 of the housing is provided with an opening II for receiving a reduced shank portion '18 of a threaded shank 19. The reduced shank extends outwardly from the end of the housing and is provided with a hand wheel which is secured on the reduced shank by suitable means, such as a socket type set screw (not shown). A cross arm 8| having a threaded center portion 82 is provided for receiving the threaded shank portion I9 and the outer ends of the arm are provided with slots 83 for receiving headed screws or stems 84 secured to the reduced ends 85 of tension springs 86. The stems 84 are provided with heads so that when tension is placed on the springs, the stems will be retained in the slots. The other ends of the tension springs are reduced as indicated at 81 and similar stems 88 are secured therein for engaging in the radial slots 40 and the heads of the stems engage around the cylindrical recesses 39 of the rear portion of the spider. Spaced from the end of the threaded shank I9 is an opening adapted to receive a cotter key 89 for preventing accidental displacement of the threaded shank from the arm.

The raised plate member 41 of the flat top of the housing 4| near the rear end thereof is cut out forming a slot 90 which is adapted to receive a horizontal arm 9| of the back member 92. A plate 93 engages over the raised plate member 41 and is provided with spaced threaded openings adapted to receive threaded shanks of bolts 94 which extend into aligned openings in the horizontal arm 9| and the raised plate member 41 to secure the horizontal arm to the top of the housing 4|. The plate 93 is also secured to the top of the housing by threaded bolts 95. The respective ends of the plate extend outwardly and upwardly from the raised plate member 41 in spaced relation to the top plate of the housing for a purpose later described. The back portion 92 has an enlarged upper end 96 provided with an opening 91 for receiving a pin 98 for hingedly connecting a back adjusting member 99. The

back adjusting member comprises a hollow member substantially rectangular in shape and has an open bottom end I90 and a slot I 0| at its upper end for receiving the lower end I02 of a spring arm I03 to which the back portion 8 is attached. The upper end of th housing 99 of the back adjusting member is provided with forwardly extending ears I04 which engage the pin 96 for hingedly connecting the members toether.

The back 8 comprises an outer plate I05 and an inner plate I06 spaced apart as best illustrated in Fig. 2. The upper end of the spring back atthat point the user is sitting in a substantially balanced position whereby slight movement forwardly will again cause the chair seat to assume the horizontal position, the back being resiliently mounted so it will follow the back of the user at 1 all times.

' The tension of the springs 86 are controlled by the hand wheel 80 whereby adjustment is made to accommodate persons of different weight. The heavier the person the greater tension is necessary on the springs and, of course,

the converse is true where lighter persons are using the chair. The tension spring mechanism also tends to maintain the chair seat in substantially horizontal position as well as to provide the desired resistance to the backward leaning action of'the user on the back of the chair. The forward portion l6 of the spider l3 will contact the bumper is which provides a resilient stop thereof, and when the chair is tilted backwardly, the.

rear portion 19 of the spider l3 will contact the bumper M which provides a cushion effect to the tilting mechanism.

The upholstery on the chair seat, arms and back is removable should it become worn or for other reasons should have to be replaced.

It will be'obvious from the foregoing that I have provided an improved posture chair whereby the seat is mounted to assume a substantially balanced position when the chair is tilted backwardly and wherein the seat goes forwardly and the forward portion upwardly coordinately with the movement of the body of the user and have also provided a resiliently mounted and adjustably tiltable back portion to accommodate persons of different sizes and weights.

What I claim and desire to secure by Letters Patent is:

'1. A chair comprising, a support, a spider mounted on said support, a tilting mechanism mounted on said spider, a seat mounted on said tilting mechanism, and a back mounted on said tilting mechanism, said tilting mechanism including cam plates having flanges forming tracks, said spider having cam rollers engaging said tracks whereby said seat will move forwardly and the front portion upwardly with respect to the support as the occupant leans backwardly.

2. A chair comprising, a support, a spider mounted on said support, a tilting mechanism mounted on said spider, a seat mounted on said tilting mechanism, and a back mounted on said tilting mechanism, said tilting mechanism including spaced cam plates having flanges forming tracks, one end of said plates being enlarged and slightly arcuate-shaped and forming tracks at an angle to the other tracks, said spider having cam rollers engaging said tracks whereby said seat will move forwardly and the front portion upwardly with respect to the support as the occupant leans backwardly.

3. A chair comprising, a supporting pedestal, a spider rotatably mounted on said pedestal, a tilting mechanism mounted on said spider including a frame, a seat mounted on said frame, a back mounted on said tilting mechanism, said tilting mechanism including cam plates secured to the inner walls of said frame and having flanges forming tracks, said spider having cam rollers engaging said tracks whereby said seat will move forwardly and the front portion thereof upwardly with respect to the support as the occupant leans backwardly, and means on the spider having engagement with the frame for preventing lateral movement of the frame relative to the spider.

4. A chair comprising, a supporting 'pedestaLa spider rotatably mounted on said pedestal, a housing for said spider having cam plates secured to the respective inner walls thereof, said cam plates having enlarged rear ends and having substantially horizontal tracks near their forward ends and slightly arcuate tracks at their rear ends, cam rollers carried by the respective ends of said spider engaging said tracks, a seat on said housing, spring tension means interconnected with the housing and spider for'normally maintaining the seat in horizontal position, and a back mounted on said housing.

5. A chair comprising, a support, a spider mounted on said support, a tilting mechanism mounted on said spider including a frame slidably mounted thereon, a seat on said frame, a back mounted on said tilting mechanism, said tilting mechanism including cam plates having flanges forming tracks, one end of each of said plates being enlarged and one of the tracks being slightly arcuate and at an angle to the other track, said spider having cam rollers engaging said tracks whereby said seat will move forwardly and the front portion upwardly with respect to the support as the occupant leans backwardly, and means interconnecting said frame and said tilting mechanism for moving the frame and seat forwardly and backwardly with respect to said back. 6. A chair comprising, a support, a spider mounted on said support, atilting mechanism mounted on said spider, a seat mounted on said tilting mechanism and having a rubber bumper around the lower forward edge thereof, a back mounted on said tilting mechanism, said tilting mechanism including cam plates having flanges forming tracks, one end of each of said plates being enlarged and one of the tracks being slightly arcuate and at an angle to the other track, said spider having cam rollers engaging said tracks whereby said seat will move forwardly and the front portion upwardly with respect to the support as the occupant leans backwardly, and bumper means for said spider at the extreme ends of said tracks.

7. A chair comprising, a support, aspider mounted on said support, a tilting mechanism mounted on said spider, a seat mounted on said tilting mechanism, a back mounted on said tilting mechanism, said tilting mechanism including cam plates having flanges forming tracks, one end of each of said plates being enlarged and one of the tracks being slightly arcuate and at an angle to the other track, said spider having cam rollers engaging said tracks whereby said seat will move forwardly and the front portion thereof upwardly with respect to the support as the occupant leans backwardly, bumper means for said spider at the extreme ends of said tracks, and means on said spider having engagement with said tracks for preventing lateral movement of the tilting mechanism with respect to said spider.

8. A chair comprising, a supporting pedestal, a spider rotatably mounted on said pedestal having laterally extending arms at its respective ends, a housing for said spider having cam plates with laterally turned flanges secured to the respective inner walls thereof, said cam plates having enlarged rear ends and said flanges forming horizontal tracks toward their forward ends and tracks at their rear ends extending at an angle to the horizontal tracks, cam rollers carried by the respective ends of the arms of said spider en- 9 gaging said tracks, rollers on the arms of said spider engaging the flanges of said tracks for retaining the housing in longitudinal alignment with the spider, a seat on said housing, spring tension means interconnected with the housing and spider for normally maintaining the seat in horizontal position, and a back mounted on said housing.

ROY A. CRAMER.

REFERENCES CITED The foilowing references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,909,018 Sengpiel May 16, 1933 1,986,105 Foote Jan. 1, 1935 5 Fox Mar. 1, 1949 

